Concurrency.swift

import SwiftUI
import UIKit
import Foundation
import Combine

enum RequestError: Error {
    case apiError(reason: String)
}

class ResultController: ObservableObject {
    @Published var senetence: String = ""
    @Published var sentiment: String = ""
    @Published var image: UIImage?

    private func giveMeACat() async throws -> UIImage {
        let imageUrl: String = try await getJSONResult(url: "https://api.thecatapi.com/v1/images/search", key: "url")
        let (data, _) = try await URLSession.shared.data(from: URL(string: imageUrl)!, delegate: nil)
        if let image = UIImage(data: data) {
            return image
        } else {
            throw RequestError.apiError(reason: "The image data is broken")
        }
    }

    private func getSentiment(sentence: String) async throws -> (String, String) {
        var request = URLRequest(url: URL(string: "https://sentim-api.herokuapp.com/api/v1/")!)
        request.allHTTPHeaderFields = ["Content-Type": "application/json" ]
        request.httpMethod = "POST"
        request.httpBody = try JSONSerialization.data(withJSONObject: ["text": sentence], options: .prettyPrinted)
        let (data, _) = try await URLSession.shared.data(for: request, delegate: nil)

        if let json = try JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [String: Any],
           let result = json["result"] as? [String: Any],
           let type = result["type"] as? String {
            return (sentence, type)
        } else {
            throw RequestError.apiError(reason: "JSON parse error")
        }
    }

    private func giveMeAJoke() async throws -> String {
        return try await getJSONResult(url: "https://api.chucknorris.io/jokes/random", key: "value")
    }

    private func getJSONResult(url: String, key: String) async throws -> String {
        let (data, _) = try await URLSession.shared.data(from: URL(string: url)!, delegate: nil)

        if let json = try JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [String: Any],
            let result = json[key] as? String {
            return result
        } else if let json = try JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [[String: Any]],
                  let result = json.first?[key] as? String {
            return result
        } else {
            throw RequestError.apiError(reason: "JSON parse error")
        }
    }

    private func fetchResult() async -> (joke: String, image: UIImage, sentiment: String)?  {
        do {
            async let joke = await self.giveMeAJoke()
            async let catImage = await self.giveMeACat()
            let (sentence, senti) = try await self.getSentiment(sentence: await joke)
            return try await (sentence, catImage, senti)
        } catch {
            print(error)
            return nil
        }
    }

    func generateANewJoke() {
        DispatchQueue.global().async {
            detach {
                if let (sentence, image, sentiment) = await self.fetchResult() {
                    DispatchQueue.main.async {
                        self.senetence = sentence
                        self.sentiment = sentiment
                        self.image = image
                    }
                }
            }
        }
    }
}

struct ContentView: View {
    @ObservedObject var controller = ResultController()

    var body: some View {
        VStack {
            controller.image.map {
                Image(uiImage: $0)
                    .resizable()
                    .scaledToFit()
                    .frame(width: 200, height: 200)
            }

            Text(controller.senetence)
                .padding(.horizontal, 20)
                .padding(.bottom, 10)

            if !controller.sentiment.isEmpty {
                HStack(alignment: .center) {
                    Text("This story is: ")
                    Text(controller.sentiment)
                        .font(Font.largeTitle)
                }
            }
            Spacer()
            Button("Random") {
                controller.generateANewJoke()
            }.padding(.bottom, 20)
        }

    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}